For a cutting insert used for this type of grooving and parting-off, for example the following Patent Document 1 has proposed a cutting insert in which: corner cutting edges are included between each lateral cutting edge (side cutting edge) and the major cutting edge (front cutting edge); each corner cutting edge includes a primary curved cutting edge that extends from the major cutting edge; furthermore, a curved wiper cutting edge extends from the curved cutting edge to the lateral cutting edge; the curvature of the primary curved cutting edge has a smaller radius than that of the curved wiper cutting edge; and moreover, the lateral edges also have a smaller radius of curvature than the radius of curvature of the curved wiper cutting edge. Patent Document 1 states that it can produce an improved surface finish whereby subsequent finishing processing can be omitted.
Furthermore, cutting inserts are also disclosed in the following Patent Documents 2 to 4. Among them, for example Patent Document 4 proposes one that has an end cutting edge (front cutting edge) formed by the intersecting ridge of a cutting face and a front flank, side cutting edges, being intersecting ridges of the cutting face and side flanks, and arc shaped corner cutting edges, which are formed between the end cutting edge and the side cutting edges, wherein wiper cutting edges with a straight line shape are formed between the corner cutting edges and the side cutting edges, parallel to the longitudinal direction of the insert body, or such that they recede as they approach the side cutting edges at a shallower taper angle than that of the side cutting edges.    Patent Document 1: Published Japanese translation No. 2002-516185 of PCT International Publication    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. H08-71806    Patent Document 3: Japanese Unexamined Patent Application, First Publication No. H10.58205    Patent Document 4: Japanese Unexamined Patent Application, First Publication No. 2006-272509